Use of the isopycnic plots in designing operations of supercritical fluid chromatography: IV. Pressure and density drops along columns

Performance of the same column in supercritical fluid chromatography and in liquid chromatography

“…Especially around the supercritical point, the density of the supercritical fluid varies strongly with the change of the pressure or temperature [21,22]. By changing the flow-rate, i.e.…”

“…The emerging average flow-rate is usually less than it is provided by the movements of the pump pistons. Since the pressure drop along the column was relatively small at the examined mobile phase velocities, the setted volumetric flow-rate compliance well to the real average volumetric flow-rate of the mobile phase [22,[25][26][27]. The actual flow-rate was checked with the comparison of the interstitial velocities calculated from the set flow-rate and the corresponding velocities calculated from the retention time of the unretained marker.…”

Insights into chiral recognition mechanisms in supercritical fluid chromatography V. Effect of the nature and proportion of alcohol mobile phase modifier with amylose and cellulose tris-(3,5-dimethylphenylcarbamate) stationary phases

“…Recently, Tarafder et al discussed the effect of pressure and density in the sub-and super-critical area. It was recommended to operate under conditions of low compressibility of CO 2 to avoid mobile phase variation along the column and poor column efficiency [22]. However, it is possible that solvents with different viscosities will result in different peak efficiencies.…”

Use and practice of achiral and chiral supercritical fluid chromatography in pharmaceutical analysis and purification

“…For neat CO 2 , the density varies from 0.2 to 1.1 g/mL. The change of density influences solubility and can dramatically modify retention factors . With the addition of high modifier proportion, the pressure variation has a lower impact on density and thus on retention.…”